All gastroenterologists, whether physicians or surgeons, will recognise a group of patients who have typical gall bladder pain but in whom imaging of the biliary tree remains obstinately negative. Incalculable numbers of acalculous patients, many of them middle-aged women, end up having a cholecystectomy almost by default. The results are surprisingly successful, perhaps owing to the powerful placebo effect of a surgical operation. Thus “blind” cholecystectomy relieved the pain in up to 70% of such patients in two historical series as opposed to the 80–85% that could be anticipated in those with symptomatic gallstones.1 ,2 The source of pain in such patients may lie within the biliary tract even if it cannot be clearly recognised. Chronic acalculous cholecystitis is the commonest suggested cause, but its definition varies between reports and is often not stated. Hyperplastic cholecytoses such as cholesterosis and adenomyosis (diverticulosis) may cause symptoms that are improved by cholecystectomy even in the absence of concomitant stones.3 The so called “cystic duct syndrome” is thought to result from postinflammatory stenosis or congenital tortuosity of the cystic duct and might cause right hypochondrical pain by inhibiting normal gall bladder emptying. In those without any clear pathological diagnosis, there could be a painful dysmotility due to asynchronous …